mozjs_sys 0.67.1

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "frontend/CallOrNewEmitter.h"

#include "frontend/BytecodeEmitter.h"
#include "frontend/NameOpEmitter.h"
#include "frontend/SharedContext.h"
#include "vm/Opcodes.h"
#include "vm/StringType.h"

using namespace js;
using namespace js::frontend;

using mozilla::Maybe;

AutoEmittingRunOnceLambda::AutoEmittingRunOnceLambda(BytecodeEmitter* bce)
    : bce_(bce) {
  MOZ_ASSERT(!bce_->emittingRunOnceLambda);
  bce_->emittingRunOnceLambda = true;
}

AutoEmittingRunOnceLambda::~AutoEmittingRunOnceLambda() {
  bce_->emittingRunOnceLambda = false;
}

CallOrNewEmitter::CallOrNewEmitter(BytecodeEmitter* bce, JSOp op,
                                   ArgumentsKind argumentsKind,
                                   ValueUsage valueUsage)
    : bce_(bce), op_(op), argumentsKind_(argumentsKind) {
  if (op_ == JSOP_CALL && valueUsage == ValueUsage::IgnoreValue) {
    op_ = JSOP_CALL_IGNORES_RV;
  }

  MOZ_ASSERT(isCall() || isNew() || isSuperCall());
}

bool CallOrNewEmitter::emitNameCallee(JSAtom* name) {
  MOZ_ASSERT(state_ == State::Start);

  NameOpEmitter noe(
      bce_, name,
      isCall() ? NameOpEmitter::Kind::Call : NameOpEmitter::Kind::Get);
  if (!noe.emitGet()) {
    //              [stack] CALLEE THIS
    return false;
  }

  state_ = State::NameCallee;
  return true;
}

MOZ_MUST_USE PropOpEmitter& CallOrNewEmitter::prepareForPropCallee(
    bool isSuperProp) {
  MOZ_ASSERT(state_ == State::Start);

  poe_.emplace(bce_,
               isCall() ? PropOpEmitter::Kind::Call : PropOpEmitter::Kind::Get,
               isSuperProp ? PropOpEmitter::ObjKind::Super
                           : PropOpEmitter::ObjKind::Other);

  state_ = State::PropCallee;
  return *poe_;
}

MOZ_MUST_USE ElemOpEmitter& CallOrNewEmitter::prepareForElemCallee(
    bool isSuperElem) {
  MOZ_ASSERT(state_ == State::Start);

  eoe_.emplace(bce_,
               isCall() ? ElemOpEmitter::Kind::Call : ElemOpEmitter::Kind::Get,
               isSuperElem ? ElemOpEmitter::ObjKind::Super
                           : ElemOpEmitter::ObjKind::Other);

  state_ = State::ElemCallee;
  return *eoe_;
}

bool CallOrNewEmitter::prepareForFunctionCallee() {
  MOZ_ASSERT(state_ == State::Start);

  // Top level lambdas which are immediately invoked should be treated as
  // only running once. Every time they execute we will create new types and
  // scripts for their contents, to increase the quality of type information
  // within them and enable more backend optimizations. Note that this does
  // not depend on the lambda being invoked at most once (it may be named or
  // be accessed via foo.caller indirection), as multiple executions will
  // just cause the inner scripts to be repeatedly cloned.
  MOZ_ASSERT(!bce_->emittingRunOnceLambda);
  if (bce_->checkRunOnceContext()) {
    autoEmittingRunOnceLambda_.emplace(bce_);
  }

  state_ = State::FunctionCallee;
  return true;
}

bool CallOrNewEmitter::emitSuperCallee() {
  MOZ_ASSERT(state_ == State::Start);

  if (!bce_->emitThisEnvironmentCallee()) {
    //              [stack] CALLEE
    return false;
  }
  if (!bce_->emit1(JSOP_SUPERFUN)) {
    //              [stack] CALLEE
    return false;
  }
  if (!bce_->emit1(JSOP_IS_CONSTRUCTING)) {
    //              [stack] CALLEE THIS
    return false;
  }

  state_ = State::SuperCallee;
  return true;
}

bool CallOrNewEmitter::prepareForOtherCallee() {
  MOZ_ASSERT(state_ == State::Start);

  state_ = State::OtherCallee;
  return true;
}

bool CallOrNewEmitter::emitThis() {
  MOZ_ASSERT(state_ == State::NameCallee || state_ == State::PropCallee ||
             state_ == State::ElemCallee || state_ == State::FunctionCallee ||
             state_ == State::SuperCallee || state_ == State::OtherCallee);

  bool needsThis = false;
  switch (state_) {
    case State::NameCallee:
      if (!isCall()) {
        needsThis = true;
      }
      break;
    case State::PropCallee:
      poe_.reset();
      if (!isCall()) {
        needsThis = true;
      }
      break;
    case State::ElemCallee:
      eoe_.reset();
      if (!isCall()) {
        needsThis = true;
      }
      break;
    case State::FunctionCallee:
      autoEmittingRunOnceLambda_.reset();
      needsThis = true;
      break;
    case State::SuperCallee:
      break;
    case State::OtherCallee:
      needsThis = true;
      break;
    default:;
  }
  if (needsThis) {
    if (isNew() || isSuperCall()) {
      if (!bce_->emit1(JSOP_IS_CONSTRUCTING)) {
        //          [stack] CALLEE THIS
        return false;
      }
    } else {
      if (!bce_->emit1(JSOP_UNDEFINED)) {
        //          [stack] CALLEE THIS
        return false;
      }
    }
  }

  state_ = State::This;
  return true;
}

// Used by BytecodeEmitter::emitPipeline to reuse CallOrNewEmitter instance
// across multiple chained calls.
void CallOrNewEmitter::reset() {
  MOZ_ASSERT(state_ == State::End);
  state_ = State::Start;
}

bool CallOrNewEmitter::prepareForNonSpreadArguments() {
  MOZ_ASSERT(state_ == State::This);
  MOZ_ASSERT(!isSpread());

  state_ = State::Arguments;
  return true;
}

// See the usage in the comment at the top of the class.
bool CallOrNewEmitter::wantSpreadOperand() {
  MOZ_ASSERT(state_ == State::This);
  MOZ_ASSERT(isSpread());

  state_ = State::WantSpreadOperand;
  return isSingleSpreadRest();
}

bool CallOrNewEmitter::emitSpreadArgumentsTest() {
  // Caller should check wantSpreadOperand before this.
  MOZ_ASSERT(state_ == State::WantSpreadOperand);
  MOZ_ASSERT(isSpread());

  if (isSingleSpreadRest()) {
    // Emit a preparation code to optimize the spread call with a rest
    // parameter:
    //
    //   function f(...args) {
    //     g(...args);
    //   }
    //
    // If the spread operand is a rest parameter and it's optimizable
    // array, skip spread operation and pass it directly to spread call
    // operation.  See the comment in OptimizeSpreadCall in
    // Interpreter.cpp for the optimizable conditons.

    //              [stack] CALLEE THIS ARG0

    ifNotOptimizable_.emplace(bce_);
    if (!bce_->emit1(JSOP_OPTIMIZE_SPREADCALL)) {
      //            [stack] CALLEE THIS ARG0 OPTIMIZED
      return false;
    }
    if (!bce_->emit1(JSOP_NOT)) {
      //            [stack] CALLEE THIS ARG0 !OPTIMIZED
      return false;
    }
    if (!ifNotOptimizable_->emitThen()) {
      //            [stack] CALLEE THIS ARG0
      return false;
    }
    if (!bce_->emit1(JSOP_POP)) {
      //            [stack] CALLEE THIS
      return false;
    }
  }

  state_ = State::Arguments;
  return true;
}

bool CallOrNewEmitter::emitEnd(uint32_t argc, const Maybe<uint32_t>& beginPos) {
  MOZ_ASSERT(state_ == State::Arguments);

  if (isSingleSpreadRest()) {
    if (!ifNotOptimizable_->emitEnd()) {
      //            [stack] CALLEE THIS ARR
      return false;
    }

    ifNotOptimizable_.reset();
  }
  if (isNew() || isSuperCall()) {
    if (isSuperCall()) {
      if (!bce_->emit1(JSOP_NEWTARGET)) {
        //          [stack] CALLEE THIS ARG.. NEW.TARGET
        return false;
      }
    } else {
      // Repush the callee as new.target
      uint32_t effectiveArgc = isSpread() ? 1 : argc;
      if (!bce_->emitDupAt(effectiveArgc + 1)) {
        //          [stack] CALLEE THIS ARR CALLEE
        return false;
      }
    }
  }
  if (beginPos) {
    if (!bce_->updateSourceCoordNotes(*beginPos)) {
      return false;
    }
  }
  if (!bce_->markSimpleBreakpoint()) {
    return false;
  }
  if (!isSpread()) {
    if (!bce_->emitCall(op_, argc)) {
      //            [stack] RVAL
      return false;
    }
  } else {
    if (!bce_->emit1(op_)) {
      //            [stack] RVAL
      return false;
    }
  }

  if (isEval() && beginPos) {
    uint32_t lineNum = bce_->parser->errorReporter().lineAt(*beginPos);
    if (!bce_->emitUint32Operand(JSOP_LINENO, lineNum)) {
      return false;
    }
  }

  state_ = State::End;
  return true;
}